[zozbot234]

> Do you think that is the way that a professional should act towards others in their profession?

That's beside the point, since not being rude to others for no reason is very much part of mainstream professional norms. The question you might ask yourself is rather: "is this one person acting violently towards the meetup organizer by not using their preferred pronouns and updated name". There are people who would answer this in the affirmative, but this implies a pretty loose understanding of what qualifies as "violence" in the first place, which leads to all sorts of unforeseen implications. There's a very good reason why etiquette is generally regarded as trivial when compared with more tangible ethical challenges, and "use the correct pronouns, styles and honorifics when addressing So-and-so" is the quintessential example of etiquette.